Nonjamming housing and cover assembly



July 23, 1968 A. I. APPLETON NONJAMMING HOUSING AND COVER ASSEMBLY Filed Feb. 15, 1967 f: VEN Ann-w: 61 116%., MM,

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United States Patent 01 3,393,824 Patented July 23, 1968 hce 3,393,824 NONJAMMING HOUSING AND COVER ASSEMBLY Arthur I. Appleton, 1701 Wellington Ave., Northbrook, Ill. 60657 Filed Feb. 15, 1967, Ser. No. 616,358 6 Claims. (Cl. 220-39) ABSTRACT OF THE DISCLOSURE A cylindrical housing for an electrical receptacle externally threaded at one end, and an internally threaded cover therefor. Mutually aligned stops on the housing and cover interferingly engage before the cover is fully turned on the housing, and a spring on the cover keeps it from loosening.

Background of the invention The present invention relates to electrical connector housings having screw-on covers and more particularly to improvements which prevent such covers from becoming jammed on the housings.

Housings for electrical receptacles are frequently provided with a cover which may be screwed on the housing to prevent exposure of the receptacle. This is particularly true in the case of receptacles designed for use in hazardous locations where the cover may serve not only to protect the receptacle from the elements, but also to prevent exposure of live electrical contacts to explosive fumes.

A problem which has been encountered with receptacle housings having threaded covers is that the cover may jam on the housing even without excessive tightening, due to corrosion when the enclosure has been left exposed to the elements. This may result in great inconvenience when access is sought to the receptacle, and, indeed, may vitiate the very purpose of the cover by leading those who use it to tighten it insufiiciently lest it become impossible to remove.

It is therefore an object of the invention to provide an improved housing and cover assembly which cannot become jammed, regardless of how firmly the cover is turned on the housing. It is a related object of the invention to provide such an assembly which not only resists jamming, but which also prevents accidental loosening of the cover on the housing.

Brief description of the drawings Other objects and advantages will become apparent from the following description and from the accompanying drawings in which:

FIGURE 1 is a partially cut away side view of the cover and housing before assembly;

FIG. 2 is a plan view, partially broken away, of the top end of the housing;

FIG. 3 is a bottom view of the cover;

FIG. 4 is a plan view, partially broken away, of the housing and of the cover assembled thereon; and

FIG. 5 is a cross-section along lines 5--5 of FIG. 4.

While the invention is susceptible of various modifications and alternative constructions, there is shown in the drawings and will herein be described in detail a preferred embodiment. It is to be understood, however, that it is not thereby intended to limit the invention to the specific form disclosed. On the contrary, it is intended to cover all modifications and alternative constructions falling within the spirit and scope of the invention as expressed in the appended claims.

Description 0] the illustrative embodiment Referring more particularly to the drawings, there is shown a cylindrical housing 11 extending from a flat base 13 and typically enclosing an electrical connector (not shown). To mount the housing, a pair of bolts 15 and 17 extend through the base 13. The housing 11 terminates in an annular end face 19 and has a series of threads 21 extending from the end face 19 toward the base 13.

To provide protection for the components enclosed within the housing 11, a threaded cover 23 is provided. In order to prevent loss of the cover 23, it may be conveniently held on the base 13 by means of a chain 25 which is attached at one of its ends to the base by the mounting bolt 17 and at its other end to the cover 23 by means of a screw 27.

Forming the cover 23 are an end wall 29 and a rim 31, the latter having a series of internal threads 33 for engagement with the external threads 21 of the housing 11.

In accordance with the invention, jamming of the cover 23 on the housing 11 is prevented by a pair of cooperating stop members 35 and 37. The first stop member 35 extends radially inward from the wall 39 of the housing 11. The other stop member 37 extends from the inside surface of the cover end wall 29, extending downwardly within but spaced from the rim 31. Preferably the stop 37 is integral with the cover 23 and, as best seen in FIG. 4, is so positioned on the end wall 29 that, as the cover is turned on the housing 11, clockwise as seen in FIG. 4,

" it eventually abuts the stop 35 on the housing. Stated in terms of the distances of the respective stops from the axes of the cover and of the housing, the cover stop 37 must extend from the longitudinal axis of the cover 23 by a distance D2 which is greater than D1, the distance of the housing stop 35 from the longitudinal axis of the housing 11.

In order to permit the cover 23 to be turned by a sufiicient number of turns but not enough to jam or bind, the length L of the cover stop 37 is chosen so that it does not abut the housing stop 35 until the end of the desired travel of the cover 23 has been reached. This point is selected to occur before there has been any binding between the cover 23 and the housing 11.

In accordance with another aspect of the invention, means are also provided for preventing the cover 23 from becoming loose. Resilient means are mounted on the cover for frictionally engaging the end wall 19 of the housing 11 before the stops 35 and 37 abut. Additional turning after engagement between the resilient means on the cover and the end face of the housing results in further increase in friction between cover and housing until the cover 23 is finally stopped. According to the preferred embodiment of this aspect of the invention, the resilient means is a leaf spring, cantilever mounted at one of its ends on the end wall 29 by means of a screw 41. As seen in FIGS. 3 and 4, the spring 39 extends along an are near the periphery of the cover 23 and an alignment with the annular end face 19 of the housing 11. As shown in FIG. 1, the spring extends away from the cover end face 29 and has a detent 43 at its free end.

After the cover 23 has been screwed down on the housing 11, the spring detent 43 begins to ride on the housing end face 19. As the cover 23 continues to be turned, the spring 39 is increasingly deflected toward the cover end wall 29. With increased deflection of the spring 39, the friction created between the cover 23 and the housing 11 is also increased until further turning of the cover 23 is terminated by abutment of the stop 37 against the stop 35. In keeping with the invention, the distance of the spring detent 43 from the cover end wall 29 is chosen to be such that the detent engages the housing end face 19 before the cover stop 37 abuts against the housing stop 35.

To increase the effectiveness of the friction spring 39 and in further keeping with the invention, surface irregularities may be added to the end face 19 in order to increase the friction between it and the spring 39. Such surface irregularities may take the form of small ridges, serrations, or, as shown in FIGS. 1 and 5, small slots 44.

While an illustrative embodiment has been described above, it will be apparent that modifications may be made Without departing from the scope of the invention. For example, although the :housing stop 35 has been shown as having its upper face level with the end surface 19, this need not necessarily be so and the housing stop 35 would function just as well if it were lowered or recessed below the housing end face 1?. To compensate for this, the cover stop member 37 would be correspondingly increased in length so as to keep the number of turns that can be made on the cover 23 before abutment between the stop members 35 and 37 the same.

Similarly, a leaf spring has been shown for causing frictional engagement between the housing 11 and the cover 23. While this is normally preferred, other resilient means could be used in its place. For example, a springloaded nylon plunger might be placed where the screw 41 is shown in FIG. 1 and might under some circumstances be preferred over the leaf spring illustrated there. Indeed, if the cover threads 33 are sufficiently snug on the housing threads 21, there may be enough friction to keep the cover 23 on the housing 11 without the need for additional friction creating devices and in such an event, the resilient means on the cover 23 and the cooperating surface irregularities on the housing end face 19 may be dispensed with.

I claim as my invention:

1. An improved nonjamming housing and cover as sembly comprising in combination:

(a) a cylindrical housing terminating at one end in an annular end face and having external threads extending away from said face,

(b) a cover for said housing having an end wall and a rim internally threaded for engagement with said housing,

(c) resilient means mounted on said end wall and positioned for frictional engagement with and travel along said end face when said cover is approaching the end of its travel on said housing,

(d) a first stop member extending radially inward from the wall of said housing, and

(e) a second stop member depending from the end wall of said cover within said rim, positioned to abut said first stop member as the cover is turned on the housing and extending from said end wall to abut said first stop member after said resilient means has traveled a predetermined distance along said end face, and before the cover has in any way jammed on the housing.

2. The combination of claim 1 wherein said resilient means is a leaf spring normally extending away from the end wall of said cover and being deflected toward said end wall upon engagement with the end face of said housing.

3. The combination of claim 2 wherein the end face of said housing includes a plurality of peripherally distributed surface irregularities for increasing the friction between said spring and said end face.

4. The combination of claim 2 wherein said leaf spring is cantilever mounted at its leading edge and wherein said surface irregularities consist of notches in said end face.

5. An improved nonjamming housing and cover assembly comprising in combination:

(a) a cylindrical housing having external threads near one of its ends,

(b) a cover for said housing having an end wall and a room internally threaded for engagement with said housing,

(c) a first stop member inwardly extending from the wall of said housing, and

(d) a second stop member downwardly extending from the end wall of said cover within said rim, positioned to abut said first stop member as the cover is turned on the housing and extending from said end wall to abut, said first stop member before rotation of the cover on the housing is otherwise arrested.

6. An improved nonjamming housing and cover assembly comprising in combination:

(a) a cylindrical housing threaded near one of its ends,

(b) a cover for said housing having an end wall and threaded for engagement with said housing,

(0) a first stop member extending from the wall of said housing, and

(d) a second stop member downwardly extending from the end wall of said cover, positioned to abut said first stop member as the cover is turned on the housing and extending from said end wall to abut said first stop member before rotation of the cover on the housing is otherwise arrested.

No references cited.

JAMES B. MARBERT, Primary Examiner. 

